Donald and Melania’s surprise visit to Iraq

President Donald Trump has defended his decision to withdraw US forces from Syria, where they have been helping battle Islamic State militants.

In a surprise trip to Iraq, Trump said: "We're no longer the suckers, folks".

"We're respected again as a nation," the President told American servicemen and women at a base in western Iraq.

He said US military gains meant that he could withdraw 2000 forces from Syria. During his first visit to a troubled region, Trump also said he has no plans to withdraw US forces from Iraq.

President Donald Trump speaks at a hanger rally at Al Asad Air Base, Iraq. Picture: AP

"I made it clear from the beginning that our mission in Syria was to strip ISIS of its military strongholds," Trump told troops clad in fatigues at al-Asad Airbase west of Baghdad.

"Eight years ago, we went there for three months and we never left," he said.

"Now, we're doing it right and we're going to finish it off."

He said Turkish President Recep Tayyip Erdogan has agreed to take out "any remnants" of IS left in Syria.

The US presence in Syria was not meant to be "open-ended," he said, adding that other wealthy nations should pay for rebuilding Syria.

"The nations of the region must step up and take more responsibility for their future," said Trump, who said there would be a "strong, deliberate and orderly withdrawal" of US forces from Syria.

A kiss in front of the American flag. Picture: AP Photo/Andrew Harnik

Trump's trip to Iraq came a week after he stunned his national security advisers by announcing the US troop withdrawal from Syria.

Defence Secretary Jim Mattis abruptly resigned following the announcement, and Trump's decision rattled allies around the world, including in Iraq.

Trump's trip was shrouded in secrecy. Air Force One flew overnight from Washington, landing at an airbase west of Baghdad under the cover of darkness Wednesday evening.

It is his first visit with troops stationed in a troubled region.

Fifteen years after the 2003 invasion, the US still has more than 5,000 troops in Iraq supporting the government as it continues the fight against remaining pockets of resistance by the Islamic State group.

IS has lost a significant amount of territory in Iraq and Syria but is still seen as a threat. Trump, who speaks often about his support for the US military, had faced criticism for not yet visiting US troops stationed in harm's way as he comes up on his two-year mark in office.

In October, Trump said he "will do that at some point, but I don't think it's overly necessary." He later began to signal that such a troop visit was in the offing.

President Donald Trump. Picture: AP

Trump had planned to spend Christmas at his private club in Florida, but stayed behind in Washington due to the shutdown.

It's unclear whether his trip to Iraq was added after it became apparent that the government would be shut down indefinitely due to a stalemate between Trump and congressional Democrats over the president's demand for a wall along the US-Mexico border.